Abstract-Videoconferencing applications have strong latency requirements and consume large portions of a network's bandwidth. Current videoconferencing solutions are not efficiently implemented as they often rely on a central server and do not leverage network layering services. In this paper, we investigate the impact of using Scalable Video Coding and Software Defined Networking techniques on videoconferencing. Specifically we propose an algorithm capable of reducing the bandwidth consumed by videoconferencing using Software Defined Networking to compute and deploy multicast trees, as well as taking advantage of the Scalable Video Coding layering feature that allows to sacrifice video quality for usability purposes. We show that by smartly dropping video layers at specific locations in the network, the overall bandwidth usage by videoconferencing decreases, and in a separate capacity study we show that our solution allows networks to support more videoconferencing calls as compared to existing solutions.

Experimentation is typically the last step before launching a network application in the wild. However, it is often difficult to gather enough hardware resources for experimenting with a reasonably sized overlay application inside a controlled environment. Virtualization is thus a handy technique for creating such an experimentation testbed. We propose a tool called NEmu designed to create virtual dynamic networks for testing and evaluating prototypes of overlay applications with a complete control over the network topology and link bandwidths. NEmu builds host-based overlay networks by using emulators such as QEMU. We illustrate the use of NEmu in the context of a file distribution overlay application. We evaluate the impact of chained TCP connections on the application performances. We show that NEmu enables us to obtain performance results concerning data rates and delays for end hosts depending on the number of intermediate hosts and the networking parameters of the overlay. Index Terms-network virtualization, QEMU, virtual testbed, chain of TCP connections.